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Constitutive Modeling for Transient Swelling Behavior of Polymeric Hydrogel with Large Deformations

Mazaheri, Hashem | 2015

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 47318 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Naghdabadi, Reza; Sohrabpour, Saeed; Baghani, Mostafa
  7. Abstract:
  8. In this work, the mechanical behavior of smart hydrogels is studied for temperature sensitive and, pH and temperature sensitive ones. First, an equilibrium model is presented for the temperature sensitive hydrogles which is continuous and numerically stable especially in the vicinity of the phase transition temperature. The model results are validated through comparing them with the experimental data available in the literature. The model results are in good agreement with those of experiments especially for hydrogels with high cross-linking density. Then, the model is implemented in a finite element framework by which some homogeneous and inhomogeneous problems are numerically solved. Specially, behavior of a temperature sensitive micro-valve is investigated both analytically and numerically. In the next step, extending the presented temperature sensitive model, an equilibrium model is developed for pH and temperature sensitive hydrogels accounting for large deformations. Comparing with the experimental data, the model is validated. The results demonstrate the continuity and stability of the model against pH and temperature changes. Then, the model is discretized in the framework of finite element and some homogeneous and inhomogeneous swelling problems are studied utilizing the model both analytically and numerically. Finally, considering the second law of thermodynamics, the presented equilibrium model for the temperature sensitive hydrogels is extended to the transient regime. The extended model is also capable of predicting neutral hydrogels behavior. The governing equations are implemented in the finite element framework for transient problems. Thereafter, some homogeneous and inhomogeneous swelling problems are investigated which their results are in good agreement with the experimental observations. Thus, due to good agreement with the experimental results, the models presented in this work, can be implemented for investigating the behavior of the temperature sensitive and, pH and temeperature sensitive hydrogels in engineering initial and boundary value problems
  9. Keywords:
  10. Large Deformation ; Finite Element Method ; Swelling Behavior ; Smart Hydrogels ; Homogeneous Swelling ; Inhomogeneous Swelling

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